Guides are generally provided in conveyors of articles for guaranteeing the correct routing of the transported articles in their movement along the transport path. Such guides can be of various types, depending on the type of conveyor they are associated with, and on the type of articles to be transported.
A same conveyor can be, and normally is, employed for transporting articles of different nature, different shape, or also simply articles of similar nature and/or shape, but of different dimensions.
To ensure the correct routing of the different types of articles that a conveyor is intended to transport, it is necessary to be able to adjust the position of the guides.
Let for example the case be considered of an air conveyor, for transporting of bottles in plastics (PET) from a station of production of the bottles to a following station of filling of the same with the desired liquids, drinks or others.
Such a conveyor essentially includes a chamber destined to be run through by a flow of air at high speed. The chamber extends along a bottles transport path, for sections of typical length variable from some tens up to some hundreds of meters.
The chamber is open at the bottom and it is adapted to accommodate the terminal portion of the neck of the bottles. The flow of air at high speed that runs through the chamber, hitting the terminal portion of the neck of the bottles, pushes the same in the desired transport direction, thereby determining the bottles movement along the transport path.
In their movement along the transport path, the bottles are supported by a pair of support guides. The support guides are placed in correspondence of the lower opening of the chamber and they extend parallelly and one in front of the other along the transport path. Such support guides act as supports for a support collar projecting from the terminal portion of the neck of every bottle. The bottles are therefore transported by the flow of air while being hung to the support guides through the respective support collars.
It is important that the bottles, in their movement along the transport path, are maintained substantially in vertical position. This allows in fact to avoid that, due to swinging of the bottles, especially in correspondence of curved sections of the transport path, the support collar stitches on the support guides causing undesired stops of some bottle and, as a consequence, of the whole train of bottles that follows it.
With the purpose of guaranteeing that the bottles are maintained substantially in vertical position, a pair of facing side containment guides is foreseen. The side containment guides extend parallelly and facing to one another along the transport path, at a lower height compared to the two support guides. Particularly, the two side containment guides are placed in proximity of the bottom of the bottles.
The two side containment guides are generally constituted by bars of metallic or synthetic material, supported by clamps arranged in longitudinal succession along the containment guides, for instance at regular intervals of about 50 cm. The clamps are provided of tangs that enable the fixing thereof to respective supports, which are mounted to brackets or bars that are fixed to the chamber and extended downward.
To perform their function, the two side containment guides need to be positioned in such a way as to be in contact or at least to graze the bottles body when the bottles move along the transport path.
Normally, an air conveyor has to allow the transport of bottles of different shapes and dimensions, particularly of different height and different diameter, for instance bottles of capacity of 0.5 lt, 1 lt, 1.5 lt and 2 lt.
From one side, the different height of the bottles to be transported makes it necessary to have side containment guides located at different heights; from the other side, the different diameter of the bottles to be transported makes it necessary for the position of the two transport guides transversally to the transport path to be adjustable.
Typically, two or three (or even more) pairs of side containment guides are foreseen, situated at different heights, approximately corresponding to the bottom portion of bottles of different height. Since bottles of greater height normally have also greater diameter, the position of the two pairs of guides located at higher heights needs to be adjustable, so that the guides of each of such pairs of guides can be moved from an operating position to a non-operating position in which the guides do not interfere with the movement of the bottles of greater height and diameter. For instance, the two containment guides placed at the highest height, that are used for containing bottles of small height and small diameter, for instance, bottles of 0.5 lt, shall be moved to the non-operating condition, and thus moved away from the center of the transport path, when the conveyor is employed for transporting bottles of increased height and diameter, for instance bottles of 1 lt, whose side containment is guaranteed by the pair of guides at immediately lower, intermediate height. Having to transport bottles of still increased height and diameter, for instance bottles of 1.5 lt or 2 lt, for the side containment of which the pair of guides located at the lowest height is exploited, both the pairs of guides at higher heights need to be moved away from the center of the transport path.
For adjusting the position of the containment guides it is known to employ pneumatic cylinder/piston groups that, when operated, move the tangs of the clamps relative to the vertical support bars. For example, in the case three pairs of containment guides are provided, in correspondence of every clamp there is provided a first pair of cylinder/piston groups for the two containment guides at higher height and a second pair of cylinder/piston groups for the two containment guides at intermediate height (the two containment guides at lower height can be fixed, since they, also when unused, do not interfere with the movement of the bottles of smaller height).
It is clear that as a similar solution requires a high number of cylinder/piston groups, something that is undesired because it causes an increase of the costs both in terms of components and assemblage, and of maintenance.
Multiple side containment guides are also known, comprising two pairs of guides located at different heights and with increasing central gap as the height decreases, fixed through respective clamps and vertical conjunction bars to a single tang. The two or more pairs of guides are in such case integrally movable, i.e. their position cannot be individually regulated, moving the tang relative to the vertical support bar through a single cylinder/piston group. The number of cylinder/piston groups to be used is reduced, but it is necessary to use cylinder/piston groups with three operating positions: two for bringing the pairs of guides at highest height and intermediate height to the respective operating positions, and one for bringing both the pairs of guides to the non-operating position.
Cylinder/pistons groups with three operating positions are however expensive, and therefore the solution is not particularly pleasant.
In WO 2004/074146, an actuator assembly for a guide of adjustable width of a conveyor of bottles is described, in which the selection of an operating position by means of control rod 34 is an operation that is independent from the actuation of the housing 12/piston rod 14 assembly.